In conventional photography, to highlight a theme scene, a camera often focuses on a depth of the theme scene such that the theme scene is clearly imaged on an image sensor of the camera, and scenes in other depths are blurrily imaged on the image sensor.
With development of a digital imaging technology, an image processing technology, and a machine vision technology, a refocusing technology emerges. According to the refocusing technology, after an image is formed, a new focusing depth can be selected according to a user need to obtain a clear image of objects in different depths. A light field camera uses the refocusing technology. The light field camera not only can obtain intensity of each incident ray, but also can record a direction that the ray enters a lens. Therefore, when shooting an image, the light field camera not only can obtain a two-dimensional image by means of shooting, but also can calculate a depth of a scene.
The light field camera differs from an ordinary camera in that, in the light field camera, a two-dimensional microlens array is provided between the image sensor and a camera lens (a main lens), and the image sensor is located on an imaging plane of the microlens array.
According to an optical principle of the light field camera, if a higher spatial resolution (i.e., higher light ray direction precision) is obtained, an image resolution is reduced. Under a given quantity of pixels of the image sensor, the spatial resolution and the image resolution cannot be increased simultaneously. Therefore, an image resolution of a current light field camera is lower than a resolution of an ordinary camera.
An existing technical solution has proposed that a low-resolution light field mode and a high-resolution normal mode should be implemented in one camera such that a user can switch between the two modes according to a requirement. To implement switch between the two modes in the camera, a microlens array and a piece of flat glass may be disposed between a main lens and an image sensor of the camera, and switch is implemented by moving the microlens array and the flat glass into or out of an optical path. For example, when a light field camera function is used, the flat glass may be moved out of the optical path, and the microlens array may be moved into the optical path, when an ordinary camera function is used, the flat glass may be moved into the optical path, and the microlens array may be moved out of the optical path. However, it takes a relatively long time to move the microlens array into or out of the optical path, resulting in a relatively long switch time.
Therefore, how fast switch is implemented between different imaging modes of a camera is an urgent problem to be resolved.